1. Field of the Invention
The present invention relates to a hollow sphere with a mesoporous structure and a method for manufacturing the same and, more particularly, to a hollow sphere and a method for manufacturing the same, wherein the mesopores of the material for forming a shell of the hollow sphere are arranged in Ia3d cubic symmetry.
2. Description of Related Art
Recently, studies on the mesoporous material are greatly developed, in order to develop various mesoporous materials with adjustable particle size, shapes, and pore arrangements. It has been known that when different surfactants or self-assembling materials are used, or when the reaction conditions are properly adjusted, the surface properties, the pore size, and the pore structures can be controlled. Owing to the tunable pore size and pore structure, the mesoporous material can carry various compounds, drugs, bio-agents, or nano-particles, so the mesoporous material can be applied to various fields such as drug delivery, optical or magnetic resonance imaging, microcapsule, or catalytic reaction. For example, when the surface of the pore of the mesoporous material is modified with different functional groups, specific drugs can be absorbed on the surface through different intermolecular force. Furthermore, if the mesoporous material can be fabricated to become hollow, the loading amount can be largely increased. Although some studies have reported several synthetic methods for forming hollow and mesoporous spheres, the nano-sized pores are disordered. Therefore, it cannot be ensured that the hollow space is connected to the external space. Thereby, for releasing materials contained inside the hollow sphere, the releasing efficiency is not good enough.
When a hollow sphere with mesoporous structure is prepared by the method generally used in the art, core templates are first provided. Herein, the core template generally used can be a spherical hard template made of metals, metal oxides or polymers, or soft templates such as emulsions or carriers. Next, precursors and structure-directing agents are added into the reaction solution containing the core templates, and the precursors are polymerized on the outer surfaces of the core templates to form shells with mesoporous structures. In the case that the hard templates are used for preparing the hollow spheres with mesoporous structures, the particle size and the thickness of the shells of the hollow spheres can be precisely controlled. However, the hard templates have to be further removed, so the process is expensive and time-consuming. In cases that soft templates are used for the preparation of the hollow sphere with mesoporous structures, the process is complicated, and the particle size of the obtained hollow spheres is usually not uniform. Some reports have shown that the hollow spheres with mesoporous structures can be synthesized in one step, by using mixed anionic and cationic surfactants or fluoride-containing surfactants. However, the obtained hollow spheres shown in these reports do not have uniform particle size, and the thickness of the shells is difficult to control. In addition, the nanometer-sized pores are disordered. Therefore, it cannot be ensured that the hollow space is connected to the external space.
Furthermore, when the hollow spheres with mesoporous structures are applied to drug delivery, the particle size of the hollow spheres has to be 50-300 nm. However, it is difficult to prepare hollow spheres within the range of size by using the conventional methods in the art.
Therefore, it is desirable to provide a method for manufacturing hollow spheres, which can be used to prepare 50-300-nm, uniform and hollow spheres with communicating mesopores of the hollow space and the external space.